Hydraulic safety bed



. 20, 1948. R. J. HESS 2,434,848

' HYDRAUL I C. S AFETY BED Filed June 26, 19 3 2 Sheets-Sheet l 6 4 (5' 52 5O 22 26' 2 50 INVENTOR. n/

.3 I'BY Jee a 02%55,

Patented Jan. 20, 194% HYDRAULIC SAFETY BED Relza J. Hess, Chicago, IlL, assignor to American Steel Foundries;Chicago, 111., a corporation of New Jersey Application June 26, 1943, Serial No. 492,363

(Cl. 267-l) 8 Claims. :1

My invention relates to presses and more Darticu arly to a hydraulicunit which may be placed upon the bolster plate ofapress, either hydraulic or mechanical, to aiford a safety bed therefor.

IMy novel safety bed is adapted to provide a seat for the lower die or mold which is normally seated on the bolster plate of thepress, and said bed is maintained .by hydraulic pressure in an open position until a predetermined pressure is placed upon the bed by the upper die or mold mounted on the movable :press platen, at which time the bed automatically closes to prevent breaking .of various parts of "the press :byiexcessive pressure. Upon withdrawal of the :movable platen, the safety bed automatically reassumesx its normal open position.

Safety cushions known in :the'prior art 18.118 of such construction that they "must :of necessity be built into a press when the same .is manufactured; however, my :novel bed may berreadily installed in any;pressalreadybuilt, and it is therefore an object of my invention todesign a safety bed of .such construction that it :may be readily applied to pre-existing presses.

Another object of my .-invention is to decrease the amount of ,fall-away in a bed-of the above described type. This fall-away is the amount of closure which occurs by reason of the compression of the actuating fluid, generally :oil, under the'tremendous pressures which are built up in the press. While oil is sometimes regarded as a noncompressible fluid, nevertheless, it has been found that in built-in units of this type, a fallaway of approximately occurs during normal operation of the press due to compression of the oil. Mynovel unit reduces this fall-away to approximately /8', and it will be understood that this is a highly desirable improvement over prior devices.

.My novel hydraulic unit is of such construction that it may be -pl.a ced upon the bolster plate of a mechanical press andmay be connected with a pumpingsystem to convert the pressinto .a .hydraulic press.

.Inthe-drawings,

Figure 1 is a top plan view of my novel safety bed, and Figure 2 is a side elevation thereof.

Figure .3 is a sectional view taken in .the longitudinal vertical planes indicated by the line 3+3 oflFigure 1.

Figures 4 and 5 are diagrammatic illustrations showing respectively my novel unit as utilized .in a safety bed arrangement and as utilized in an arrangement to convert an associated mechanical-press into a hydraulic one.

Describing my invention in detail, the unit generally designated I comprises the bottom mem-- ber 2 in the form of a casting orforgin of generally rectangular form in plan view, said bottom member comprising the base plate or web 4 having a flat surface 6 affording a convenient seat for the unit upon the bolster plate 8 of an associated press. The'base plate is flanged at opposite ends thereof as at It, l0, said flanges being provided with openings I2, I 2 (Figure l) for the reception of means affording securement to the bolster plate 8.

At the four corners thereof the base plate A is provided with upstanding bosses hi, i l having bushed openings l6, l6 (Figure 3, left) for slidable reception of guide posts l8, i8 carried by the upper member, as hereinafter described, a port 20 communicating with each openin iii to accommodate convenient lubrication thereof.

A piston or ram 22 is seated on the base plate 4 centrally thereof and is removably secured thereto as at 24 (Figure 3 right), said ram being hollow with the central cavity 26 and the openings 28 and 3D communicating therewith to afiord passage for an associated supply line, said line extending into the cavity 26 through the opening 28 in the side of the ram and upwardly into the opening 30 through the top of the ram to sup ply actuating fluid, such as oil, through said opening 30 to the cylinder 32 formed in the top member generally designated 34. It may be noted that the opening 30 is flared at the upper extremity thereof and is formed along smooth radii to prevent foaming of the oil as it is forced through said opening30 into the cylinder 32.

The top member 34 is preferably a casting or forging having the top plate or web 36 with the fiat surface 38 on'the top thereof to afford a convenient-seat for a die or mold supported by the unit. .At therfour corners thereof the Web 3B. is formed with depending bosses or lugs 30, 40 each having'an opening 42 for the reception of a guide post I78 press-fitted therein, said post being slidably received within the adjacent opening Iiias above described to afford guide means maintaining the top and bottom members 34 and 2 in proper alignment. It may be noted that at the upper end of each opening 42 a recess-44 is formed in each boss to, and a port lfi communicates with said recess to permit pressure fluid to be conveyed thereto as a convenient means of disassembling the guide post from the opening 42. The lugs 30, ll! at each side of the web 36 are reinforced by means of an integral rib 41 extending therebetween.

It will be understood that the arrangement illustrated with the ram mounted on the bottom member 2 and. the cylinder formed on the top member 3 3 is of particuar advantage in conserving space, inasmuch as the top member must be formed of relatively thick section to accommodate bending stresses thereon and also to accommodate the cy'inder which is formed therein; and it will be understood that if the cylinder were formed in the bottom member, the latter would have to be formed of relatively thick section because of the cylinder, and the top member would also have to be formed of relatively thick section because of bending stresses placed thereon due to its position as top member. Thus, if the cylinder were formed in the bottom member, the device could not be as compact as that illustrated.

It may be noted that the member 34 at each side of the longitudinal center line thereof is formed with a rib or ledge 48 (Figure 3) disposed within the cylinder 32 for cooperation with the ram 22 to afiord stop means on the closure stroke of the unit. It will be understood that ordinarily the closure stroke is stopped or limited by the abutment of the bosses I4, I with the the adjacent surfaces of the bosses 40, 40; however, if pressure on the unit increases to a point where the top member flexes or bends at the center thereof, the ribs 28, 43 cooperate with the ram 22 to limit such bending, thus preventing breaking of the upper member. Packing means 50 of more or less conventional form is provided.

Stop means for limiting the expansion of the unit is provided in the form of bolts or pins 52, 52 mounted on the base plate 4 of the lower member 2, each bolt being slidably received within an opening 54 in a lug 56 integrally formed with the top member 34, a nut 58 being threaded on the top of the bolt 52 for abutment with said lug 56 to limit expansion of the unit.

Figures 4 and 5 are diagrammatic views showing two different applications of my novel unit, Figure 4 showing the unit utilized as a safety bed, and Figure 5 showing the unit as applied to a mechanical press to convert the same into a hydraulic press. In the arrangement of Figure 4, a tank I06 is provided, said tank being partially filled with oil to the level indicated at I 00, and I compressed air is forced into the top of the tank through the air line I I0, said line including a safety relief valve I I2. It will be understood that the oil is supplied to the tank I08 by means of the oil supply line H4, and the oil is conveyed from the tank by means of the supply line M0, the oil passing through a one-way check valve H8 and thence through the relief valve I20 into the supply line I22 which extends into the ram as illustrated in Figures 1 and 2, said line I22 communicating with the cylinder 32 through the opening 30 in the top of the ram. The relief valve I20 is set for a certain predetermined danger pressure after which the oil is released through the release line I26 and is returned to the tank I 03, thus permitting the hydraulic unit I to close. When the pressure on the unit is relieved to a point below the predetermined danger limit, the relief valve automatically closes the outlet to the line I26, and the oil flows back through the supply line I it to expand the unit to its normal open position.

Referring now to Figure 5, it will be seen that a tank 202 is filled with oil to the level indicated at 204, and compressed air is forced into the top of the tank by means of the air supply line 206. An outlet pipe or line 208 extends from the tank 202 through the pump sump 209, said pipe 208 being provided with a float control valve 2 I0 (hereinafter discussed) and a foot valve 2 I2 through which oil is pumped from the sump by means of the pump 2I4 operated by the motor 2I6. The oil is pumped through the supply line 2| 8 through the pressure control valve 2| 9 (hereinafter discussed) into the unit I for actuation of the same. A safety line 220 is provided with a safety relief valve 222 to prevent the building up of dangerous pressures by the pump. A relief line 224 communicates with the supply line 2I8 and is provided with an operating valve 226; and it will be understood that during operation of the pump 2 I4 the operating valve 226 may be partially closed, whereupon pressure will be built up in the supply line 2 I8 to urge the unit I to expanded position, thus functioning as a hydraulic press with the upper platen of the mechanical press stopped at any desired distance above the unit.

When it is desired to allow the unit to close, the operating valve 226 is opened and the oil is pumped through the line 224 back into the tank, the oil in the unit also flowing back through the line 224 to allow the unit to close. It will be understood that the float control valve 2 I0 is operable to maintain a constant oil level in the sump by releasing additional oil from the tank 202 whenever the oil in the sump reaches a predetermined level. Leaking oil from the pump is conveyed by means of the overflow pipe 228 into the sump.

It will be understood that the above described arrangement is extremely useful in adapting my novel hydraulic unit to a mechanical press for converting the same into a hydraulic press, inasmuch as a hydraulic press is essential in certain arts such as, for example, the art of plastic molding, as hereinafter discussed.

In plastic molding, the unit is placed on a bolster plate of a mechanical press, and the movable top platen thereof is lowered to any desired distance above the unit with the molds placed between the unit and said movable platen. With the movable platen stopped at the desired position, the operating valve 226 is then closed to a certain extent, and the unit expands to place the molds under the desired pressure. The valve 226 may then be opened slightly to release pressure on the molds, thus permitting a breathing operation, essential in this art; and thereafter the valve may be gradually closed to afiord a gradually increasing pressure on the molds as the curing cycle of the molded material progresses.

If it is desired to use my novel unit as a safety bed in the normal operation of the mechanical press with the system illustrated in Figure 5, the pump may be stopped and the operating valve may be opened to its fullest extent. Thereafter the pressure control valve 2I9 may be set for a certain predetermined pressure. Thus, the air pressure in the tank 202 will be efiective to urge I oil into the unit to open the same, and the pressure control valve 2I9 will be effective to prevent closing of the unit until a certain predetermined pressure is built up thereon, whereupon the valve 2I9 will permit the oil to flow back through the release line 224 and thence into the tank 202. It will be understood that the valve 2I9 will be ineffective to control flow of oil through the system until said valve is manually adjusted for this purpose. I

It is to be understood that 1? do not wish to be limited by the exact embodiments of the device shown which are merely by way of illustration and not limitation as various and other forms of the device will, of course, be apparent to those skilled in the art without departing from the spirit of the invention or the scope of the claims.

I claim:

1. In a portable hydraulic safety bed, top and bottom members each being generally rectangular in plan view, a ram mounted on said bottom member for reception within a cylinder formed in said top member, a plurality of upstanding bosses on said bottom member disposed respectively at the four corners thereof and each hav ing a vertical opening, a plurality of depending bosses on said top member in alignment respectively with said upstanding bosses, a guide post carried by each depending boss and received within the adjacent of said openings, each of said depending bosses having a bottom surface for abutment with the top surface of the adjacent upstanding boss to limit closure of the bed, ribs formed within said cylinder for abutment with said ram to afford additional limitation of the closure of said bed, pins mounted on said bottom member and slidably interlocked with said top member to limit expansion of the bed, and fluid inlet means communicating with said cylinder to afford passage of pressure fluid into said cylinder, said top member being formed with an uninterrupted flat top surface affording a seat for an associated die, and said bottom member having an uninterrupted fiat bottom surface affording a seat for saidbed upon an associated bolster plate, said posts and said pins being entirely disposed intermediate said last-mentioned top and bottom surfaces.

2. In a portable hydraulic safety bed, top and bottom members each being generally rectangular in plan view, a ram mounted on one of said members for reciprocation within a cylinder formed in the other of said members, a plurality of upstanding bosses on said bottom member disposed respectively at the four corners thereof and each having a vertical opening, a plurality of depending bosses on said top member in alignment respectively with said upstanding bosses, a guide post carried by each depending boss and slidably received within the adjacent of said openings, each of said depending bosses having a bottom surface for abutment with a top surface of the adjacent upstanding boss to limit closure of the bed, ribs formed Within said cylinder for abutment with said ram to afford additional limitation of the closure of said bed, pins mounted on said bottom member and slidably interlocked with lugs on said top member to limit expansion of the bed, and a fluid pressure supply line communicating with said cylinder, said top member being formed with a flat top surface affording a seat for an associated die, and said bottom member having a fiat bottom surface affording a seat for said bed upon an associated bolster plate, said posts and said pins being entirely disposed intermediate said last-mentioned top and bottom surfaces.

3. In a portable unit of the class described, spaced members, one of said members having a plate affording a seat on one side thereof for an associated press part, the other of said members having a web affording a seat on one side thereof for another associated press part, a ram mounted on one of said members, a cylinder on the other member receiving said ram, a plurality of bosses on each member in alignment with corresponding bosses of the other member and adapted for abutment therewith to limit closure of the unit, guide means on the bosses of one member slidably received within the corresponding bosses of the other member for limiting relative rotational movement between said members, and interlocking means on respective members adapted forinterengagement to limit expansion of the unit, all of said means being entirely disposed intermediate said seats.

4. In a portable hydraulic safety bed, top and bottom members each being generally rectangular in plan view, a ram mounted on one of said mem bers for reciprocation within a cylinder formed in the other of said members, a plurality of upstanding bosses on said bottom member disposed respectively at the four corners thereof and each having a vertical opening, a plurality of depending bosses on said top member in alignment respectively with said upstanding bosses, a guide post carried by each depending boss and slidably received within the adjacent of said openings, each of said depending bosses having a bottom surface for abutment with a top surface of the adjacent upstanding boss to limit closure of the bed, ribs formed within said cylinder for abutment with said ram to afford additional limitation of the closure of said bed, and a fluid pressure supply line communicating with said cylinder, said top member being formed with a flat top surface affording a seat for an associated die, and said bottom member having a fiat bottom surface affording a seat for said bed upon an associated bolster plate, said posts being entirely disposed intermediate said flat surfaces.

5. In an hydraulic safety bed, top and bottom members each being generally rectangular in plan view, a ram mounted on said bottom member for reception within a cylinder formed in said top member, a plurality of upstanding bosses on said bottom member disposed respectively at the four corner thereof and each having a vertical opening, a plurality of depending bosses on said top member in alignment respectively with said upstanding bosses, a guide post carried by each depending boss and received within the adjacent of said openings, each of said depending bosses having a bottom surface for abutment with the top surface of the adjacent upstanding boss to limit closure of the bed, and pins mounted on said bottom member and slidably interlocked with lugs on said top member to limit expansion of the bed, said pins and said posts being entirely disposed intermediate the top and bottom surfaces of said bed.

6. In a portable hydraulic unit of the class described, upper and lower members, said members comprising, respectively, top and bottom substantially fiat uninterrupted surfaces, the lower member having a base plate affording a seat for the unit on an associated bolster plate, and the upper member having a top web affording a seat on the top thereof for an associated die, a ram mounted on said lower member, a plurality of upstanding bosses on said lower member and each having a vertical opening, said upper member having a cylinder for the reception of said ram, a plurality of depending bosses on said upper member, guide means mounted on said depending bosses and slidably received within said openings, and means on said lower member slidable interlocked with said upper member for limiting expansion of the unit, all of said means being entirely disposed intermediate said top and bottom surfaces.

7. In a portable unit of the class described, normally spaced members having seats on their remote sides for associated press parts, a, plurality of stop bosses on the adjacent sides of respective members arranged in pairs with one boss of each pair being carried by one member and the other boss carried by the other member, the bosse of each pair being adapted for abutment to limit closure of the unit, complementary interengaged cylinder and ram means on the adjacent sides of respective members, complementary slidably interengaged means on respective bosses of each pair for limiting rotational movement between ing relative rotational movement between said members, and interlocking means on respective members engageable to limit expansion of the unit, all of said means and said elements being entirely disposed between said seats, said interlocking means being spaced from and independent of said limiting means.

RELZA J. HESS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 922,392 Christianson May 18, 1909 1,066,825 Lewis July 8, 1913 1,354,785 Strand Oct. 5, 1920 1,787,996 Rode Jan. 6, 1931 1,849,619 Glasner et al. Mar. 15, 1932 1,920,547 Byerlein Aug. 1, 1933 2,148,855 Cannon Feb. 28, 1939 2,267,662 Miller Dec, 23, 1941 2,284,958 Grime June 2, 1942 

